Returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular matrix supplied in packed form.
val = slantp( norm, uplo, diag, n, ap, work )
val = dlantp( norm, uplo, diag, n, ap, work )
val = clantp( norm, uplo, diag, n, ap, work )
val = zlantp( norm, uplo, diag, n, ap, work )
The function ?lantp returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular matrix A, supplied in packed form.
CHARACTER*1. Specifies the value to be returned by the routine:
= 'M' or 'm':
val = max(abs(Aij)), largest absolute value of the matrix A.
= '1' or 'O' or 'o':
val = norm1(A), 1-norm of the matrix A (maximum column sum),
= 'I' or 'i':
val = normI(A), infinity norm of the matrix A (maximum row sum),
= 'F', 'f', 'E' or 'e':
val = normF(A), Frobenius norm of the matrix A (square root of sum of squares).
Specifies whether the matrix A is upper or lower triangular.
= 'U': Upper triangular
= 'L': Lower triangular.
Specifies whether or not the matrix A is unit triangular.
= 'N': Non-unit triangular
= 'U': Unit triangular.
INTEGER. The order of the matrix A.
n ≥ 0. When
n = 0, ?lantp is set to zero.
REAL for slantp
DOUBLE PRECISION for dlantp
COMPLEX for clantp
DOUBLE COMPLEX for zlantp
Array, DIMENSION (
The upper or lower triangular matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array ap as follows:
uplo = 'U',
AP(i + (j-1)j/2) = a(i,j)for
1≤ i≤ j;
uplo = 'L',
ap(i + (j-1)(2n-j)/2) = a(i,j)for
j≤ i≤ n.
Note that when
diag = 'U', the elements of the array ap corresponding to the diagonal elements of the matrix A are not referenced, but are assumed to be one.
REAL for slantp and clantp.
DOUBLE PRECISION for dlantp and zlantp.
Workspace array, DIMENSION
lwork ≥ nwhen
norm = 'I'; otherwise, work is not referenced.